Along with recent popularization of digital cameras, so-called direct printing, in which image data is directly transferred to a printing apparatus without using a host computer (personal computer) and is printed after data processing has been performed thereon in the printing apparatus, has become popular. In the direct printing, a digital camera is connected to a printing apparatus, and then the printing apparatus accesses a memory card in the digital camera, reads image data recorded on the memory card, and prints the image data. Alternatively, the memory card may be inserted into a card slot of the printing apparatus, so that the printing apparatus can read and print the image data recorded on the memory card.
Also, index printing, in which a plurality of small-sized images (reduced images or thumbnail images) are printed while being arranged on a printing sheet, and index display, in which a plurality of thumbnail images are displayed while being arranged on an operation screen, have been realized (hereinafter, index printing and index display are collectively called “index outputting”). In the index outputting, a plurality of arranged thumbnail images are output so that a plurality of pieces of image data recorded on a memory card or the like can be listed. By viewing the index, a user can check the content of images recorded on the memory card or can check desired images. Furthermore, by selecting desired images in a method provided by a printing apparatus, the user can print only necessary images among all the images recorded on the memory card.
According to PTL 1, a file for index printing can be selected based on a plurality of files and associated information thereof.
According to PTL 2, a plurality of files can be combined into a group, and a display layout can be controlled in units of groups.
In PTL 1 and PTL 2, however, an image data file including only a piece of image data to be selected is used as a target. In a case where an image data file including a plurality of pieces of image data is used as a target of index outputting, pieces of image data to be output are not appropriately selected.
Further, in a case where a plurality of images to be output as an index are selected from a file, it is difficult for the user to determine whether the plurality of images belong to the same file.
Still further, in a case where a plurality of images in a file are to be output as an index, it is difficult for the user to determine a relationship between the images.